Image display device and electronic apparatus

ABSTRACT

An image display device includes: pixels in first and second directions; a polarization controller providing first and second polarization axis light; and a controller. The polarization controller includes first electrodes extending in the first direction on a first substrate with a predetermined interval in the second direction, and second electrodes extending in the first direction on a second substrate with an interval in the second direction twice the predetermined interval. The controller switches display between dual-screen and three-dimensional modes. In the dual-screen mode, the controller applies voltages to the second electrodes so adjacent electrodes have opposite phases, and applies the same phase voltage as one of the second electrode voltages to the first electrodes. In the three-dimensional mode, the controller applies voltages to the first electrodes so adjacent electrodes have opposite phases, and applies the same phase voltage as one of the first electrode voltages to the second electrodes.

BACKGROUND

1. Technical Field

The present invention relates to image display devices and electronicapparatuses, and more particularly to an image display device providedwith a polarization axis controller and to an electronic apparatus.

2. Related Art

One known method for an image display device displaying athree-dimensional stereo image is a system employed in athree-dimensional image display device disclosed in Japanese Patent No.2,857,429.

In the three-dimensional image display device disclosed in JapanesePatent No. 2,857,429, an electronic parallax barrier disposed on aviewer side of an image display surface is controlled by a controller,such as a microcomputer, thereby forming apertures and light-blockingportions of the electronic parallax barrier so that an image for theleft eye enters the left eye of the viewer and an image for the righteye enters the right eye of the viewer.

However, since the electronic parallax barrier is disposed on the viewerside of the image display surface of the three-dimensional image displaydevice disclosed in Japanese Patent No. 2,857,429, part of light emittedfrom the image display surface is blocked by the light-blocking portionsof the electronic parallax barrier. As a result, the luminance of animage viewed by the viewer is reduced, and the image seems dark to theviewer.

A known dual-screen display device is available for providing differentimages to viewers at different viewing positions by disposing a barrierhaving slit apertures and light-blocking portions on a viewer side of adisplay panel. This type of display device is disadvantageous in thatpart of light emitted from the display panel is blocked by the barrier,and, as a result, an image seems dark.

SUMMARY

An advantage of some aspects of the invention is that it provides animage display device capable of displaying a three-dimensional image andfunctioning as a dual-screen display without reducing the luminance ofan image viewed by viewers.

According to an aspect of the invention, an image display deviceincludes the following elements: a display panel that has a plurality ofpixels arranged in a predetermined first direction and in a seconddirection intersecting with the first direction; a light source thatemits light to the display panel; a polarization axis controller thatseparates the light emitted from the light source into light with afirst polarization axis and light with a second polarization axisdifferent from the first polarization axis, the polarization axiscontroller being disposed between the display panel and the lightsource; and an optical element that directs the light emitted from thelight source in a direction substantially orthogonal to the firstdirection, the optical element being disposed between the display paneland the polarization axis controller. The polarization axis controllerincludes the following elements: a first substrate; a second substrate;a liquid crystal layer held between the first substrate and the secondsubstrate; a plurality of first electrodes disposed on the firstsubstrate so as to extend in the first direction, the plurality of firstelectrodes being arranged at a predetermined interval in the seconddirection; and a plurality of second electrodes disposed on the secondsubstrate so as to extend in the first direction, the plurality ofsecond electrodes being arranged at an interval twice the predeterminedinterval in the second direction. The plurality of second electrodes isdisposed so as to overlap at least part of the adjacent firstelectrodes.

With the structure of the aspect of the invention, part of light emittedfrom the display panel is not blocked by a barrier, and hence theluminance of an image viewed by viewers is not reduced. By controllingthe state in which voltages are applied to the plurality of firstelectrodes and the plurality of second electrodes of the polarizationaxis controller, the length in the second direction of first and secondpolarization-controlled areas can be controlled. Accordingly, thedirection in which light is directed can be switched using the opticalelement, and a display mode can be switched between a three-dimensionalimage display mode and a dual-screen display mode.

It is preferable that the plurality of first electrodes be a pluralityof strip electrodes of a pair of comb-like electrodes having a pair ofconnecting portions disposed along an outer periphery of the firstsubstrate and the plurality of strip electrodes extending alternatelyfrom the pair of connecting portions inward of the first substrate, andthat the plurality of second electrodes be a plurality of stripelectrodes of a pair of comb-like electrodes having a pair of connectingportions disposed along an outer periphery of the second substrate andthe plurality of strip electrodes extending alternately from the pair ofconnecting portions inward of the second substrate.

With this structure, two electrodes to which different voltages areapplied can be fabricated using a single electrically-conductive layeron each substrate, and hence a polarization-controlled liquid crystalpanel can be easily fabricated.

It is also preferable that the image display device further include acontroller that switches an image display mode between a dual-screendisplay mode and a three-dimensional image display mode by controllingvoltages applied to the plurality of first electrodes and the pluralityof second electrodes.

In this case, in the dual-screen display mode, the controller preferablyapplies voltages to the plurality of second electrodes so that theadjacent electrodes have opposite phases, and, to the plurality of firstelectrodes, preferably applies a voltage having the same phase as one ofthe voltages applied to the plurality of second electrodes. In thethree-dimensional image display mode, the controller preferably appliesvoltages to the plurality of first electrodes so that the adjacentelectrodes have opposite phases, and, to the plurality of secondelectrodes, preferably applies a voltage having the same phase as one ofthe voltages applied to the plurality of first electrodes.

With this structure, the controller can be constructed using acombination of a simple known electrical circuit, and hence thecontroller can be easily fabricated.

In this case, it is preferable that the controller apply the voltages tothe plurality of first electrodes so that the adjacent electrodes haveopposite phases and, to the second electrodes, apply a voltage with aperiod half that of the voltages applied to the plurality of firstelectrodes, thereby switching the image display mode to atwo-dimensional image display mode.

With this structure, the image display device capable of displaying afine two-dimensional image can be realized.

It is also preferable that the controller apply the voltages to theplurality of second electrodes so that the adjacent electrodes haveopposite phases, and, to the plurality of first electrodes, apply avoltage having the same phase as the other voltage applied to theplurality of second electrodes, thereby switching the image display modeto a second dual-screen display mode.

With this structure, images provided to viewers at different viewingpositions can be switched without switching the positions at which theimages are displayed on the display panel. Therefore, no imageprocessing is necessary therefor, and no delay occurs in displaying theimages when the directions in which the images are provided areswitched.

According to another aspect of the invention, an electronic apparatusincludes the above-described image display device.

With the structure of the aspect of the invention, a three-dimensionalimage with a high luminance can be displayed, while a dual-screendisplay can be realized.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the accompanyingdrawings, wherein like numbers reference like elements, and wherein:

FIG. 1 is an exploded perspective view of an image display device;

FIG. 2 is a view of a display panel viewed from the top by viewers fordescribing the principle of the image display device;

FIG. 3 is a partly enlarged view of a polarization-controlled liquidcrystal panel;

FIG. 4 is an exploded perspective view of the polarization-controlledliquid crystal panel;

FIG. 5 is a plan view of the polarization-controlled liquid crystalpanel;

FIG. 6 is a sectional view of the polarization-controlled liquid crystalpanel taken along the line VI-VI of FIG. 5;

FIG. 7 is an electrical circuit diagram of a control circuit;

FIGS. 8A to 8C are timing charts for describing voltages output fromoutput ends;

FIG. 9 is a view of the display panel viewed from the side by theviewers for describing the principle of the image display device;

FIG. 10 is an exploded perspective view of the image display device fordescribing the principle of the image display device;

FIG. 11 is a diagram for describing areas of the display panel viewed bythe viewers in a dual-screen display mode of the image display device;

FIG. 12 is a view of the display panel viewed from the top by theviewers for describing the principle of displaying a three-dimensionalimage by the image display device;

FIG. 13 is an exploded perspective view of the image display device fordescribing the principle of displaying a three-dimensional image by theimage display device;

FIG. 14 is a diagram for describing areas of the display panel viewed bythe viewers in a three-dimensional image display mode of the imagedisplay device;

FIG. 15 is a diagram showing the polarization-controlled liquid crystalpanel, a retardation film, and the display panel in a two-dimensionalimage display mode of the image display device;

FIG. 16 is a diagram for describing areas of the display panel viewed bythe viewers in the two-dimensional image display mode of the imagedisplay device;

FIG. 17 is a perspective view showing the structure of a cellular phone;

FIG. 18 is an electrical circuit diagram of a control circuit accordingto a second embodiment; and

FIGS. 19A to 19D are timing charts for describing voltages output fromoutput ends according to the second embodiment.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

A first embodiment of the invention will be described with reference toFIGS. 1 to 17.

An image display device 1 of the first embodiment has three imagedisplay modes, namely, a dual-screen display mode in which differentimages are provided to viewers 10 and 20 residing at different viewingpositions, a three-dimensional image display mode in which athree-dimensional image is provided to the viewers 10 and 20, and atwo-dimensional image display mode in which one and the sametwo-dimensional image is provided to the viewers 10 and 20. By switchingamong these image display modes, the image display device 1 can provideimages in various modes.

The structure of the image display device 1 of the first embodiment willbe described. FIG. 1 is an exploded perspective view of the imagedisplay device of the first embodiment. FIG. 2 is a view of a displaypanel viewed from the top by the viewers for describing the principle ofthe image display device of the first embodiment shown in FIG. 1. FIG. 3is a partly enlarged view of a polarization-controlled liquid crystalpanel of the image display device shown in FIG. 1. The image displaydevice 1 includes, as shown in FIGS. 1 and 2, a display panel 2 fordisplaying an image, polarization plates 3 and 4 disposed so as to havethe display panel 2 therebetween, a backlight 5 for irradiating thedisplay panel 2 with light, and a polarization plate 6 disposed on theside of the backlight 5 facing the viewers 10 and 20 (see FIG. 2). Thepolarization plates 3 and 4 disposed so as to have the display panel 2therebetween have polarization axes, namely, a first polarization axisand a second polarization axis, that are orthogonal to each other. Thepolarization plate 4 has a function of allowing light with the firstpolarization axis to pass through and absorbing light with the secondpolarization axis, which is substantially orthogonal to the firstpolarization axis. The polarization plate 3 has a function of allowinglight with the second polarization axis, which is substantiallyorthogonal to the first polarization axis, to pass through and absorbinglight with the first polarization axis. A combination of the displaypanel 2 and the polarization plates 3 and 4 corresponds to a so-calledtransmissive liquid crystal panel having a matrix of pixels arranged inan F direction and a G direction, which are orthogonal to each other.The polarization plate 6 is constructed to allow, of the light emittedfrom the backlight 5, the light with the first polarization axis to passthrough. The display panel 2 is connected to a controller 30 and candisplay an image by changing optical characteristics of each pixel inaccordance with an image signal from the controller 30. The controller30 renders image data input from an external device (not shown) to theimage display device 1 and generates an image signal.

The controller 30 is electrically connected to a drive circuit 100 ofthe a polarization-controlled liquid crystal panel 7, which will bedescribed below, and outputs a switching signal to the drive circuit 100in accordance with a change in the image display mode. In the firstembodiment, the switching signal is output on the basis of a commandinput from an external device (not shown) connected to the image displaydevice 1 to the controller 30. A command to change the image displaymode may be input manually by the viewer 10 or 20 via an input devicesuch as a switch (not shown) or may be included in image data input tothe image display device 1. The controller 30 may be provided externallyto the image display device 1.

The polarization-controlled liquid crystal panel 7 is disposed on theside of the polarization plate 6 facing the viewers 10 and 20. Thepolarization-controlled liquid crystal panel 7 is, as shown in FIG. 3, aliquid crystal panel having two transparent substrates between whichliquid crystal is held. The polarization-controlled liquid crystal panel7 has a plurality of strip-shaped unit areas 7 c arranged at pitch W inthe G direction, where the F direction serves as the longitudinaldirection. The polarization-controlled liquid crystal panel 7 isconnected to the drive circuit 100. The unit areas 7 c enter one of twostates by changing the liquid crystal alignment in the unit areas 7 c onthe basis of a signal from the drive circuit 100. The two states are atransmissive state where light with the first polarization axis isallowed to pass through and a polarization state where light with thefirst polarization axis is changed to light with the second polarizationaxis, which is substantially orthogonal to the first polarization axis.The drive circuit 100 is connected to the controller 30 and controls thestate of the unit areas 7 c on the basis of a switching signal from thecontroller 30.

The polarization-controlled liquid crystal panel 7 alternately changesthe state of the unit areas 7 c between the transmissive state and thepolarization state in units of one or two unit areas 7 c. As a result,the polarization-controlled liquid crystal panel 7 haspolarization-controlled areas 7 a for allowing light with the firstpolarization axis, which is emitted from the backlight 5 via thepolarization plate 6, to pass through, and polarization-controlled areas7 b for changing the light from having the first polarization axis tohaving the second polarization axis substantially orthogonal to thefirst polarization axis. The polarization-controlled areas 7 a and 7 bof the polarization-controlled liquid crystal panel 7 are alternatelydisposed in the G direction and extend in a direction substantiallyorthogonal to a line segment connecting a left eye 10 a (20 a) and aright eye 10 b (20 b) of the viewer 10 (20) (perpendicular to the pageof FIG. 2 (in the F direction of FIG. 1)).

For example, when the image display device 1 is in the dual-screendisplay mode, the polarization-controlled liquid crystal panel 7 iscontrolled so that two adjacent unit areas 7 c are in the transmissivestate to form one polarization-controlled area 7 a and that two nextadjacent unit areas 7 c are in the polarization state to form onepolarization-controlled area 7 b (state shown in FIG. 3). For example,when the image display device 1 is in the three-dimensional imagedisplay mode, the polarization-controlled liquid crystal panel 7 iscontrolled so that the unit areas 7 c are alternately in thetransmissive state and the polarization state to form thepolarization-controlled areas 7 a and 7 b. For example, when the imagedisplay device 1 is in the two-dimensional image display mode, thepolarization-controlled liquid crystal panel 7 is controlled so that theunit areas 7 c are alternately in the transmissive state and thepolarization state to form the polarization-controlled areas 7 a and 7 band that the polarization-controlled areas 7 a and 7 b are periodicallyswitched.

As shown in FIGS. 1 and 2, a lenticular lens 8 is disposed on the sideof the polarization-controlled liquid crystal panel 7 facing the viewers10 and 20. The lenticular lens 8 includes a plurality of substantiallysemi-cylindrical lens portions 8 a extending in the F direction ofFIG. 1. The lenticular lens 8 including the lens portions 8 a has afunction of guiding light separated by the polarization-controlledliquid crystal panel 7 into two beams with different polarization axesto the viewers 10 and 20 in two directions substantially orthogonal tothe F direction. That is, the directions in which the light is guided bythe lenticular lens 8 are directions toward the viewers 10 and 20 atdifferent viewing positions in the dual-screen display mode and aredirections toward the right eye 10 b (20 b) and the left eye (10 a) ofthe viewer 10 (20) in the three-dimensional image display mode.

A retardation film 9 is disposed between the lenticular lens 8 and thepolarization plate 4 attached to the display panel 2. FIG. 9 is a viewof the display panel viewed from the side by the viewers for describingthe principle of the image display device shown in FIG. 1. FIG. 10 is anexploded perspective view of the image display device for describing theprinciple of the image display device shown in FIG. 1. The retardationfilm 9 includes transmissive areas 9 a for allowing light with the firstpolarization axis to pass through and polarization areas 9 b forchanging light with the first polarization axis to light with the secondpolarization axis. As shown in FIGS. 1 and 10, the transmissive areas 9a and the polarization areas 9 b extend in the G direction substantiallyorthogonal to the F direction and are alternately disposed in the Fdirection. As shown in FIGS. 9 and 10, the transmissive areas 9 a andthe polarization areas 9 b of the retardation film 9 are disposed inassociation with pixel rows 2 a and 2 b that extend in the G directionof the display panel 2 and that are alternately disposed in the Fdirection.

The structure of the polarization-controlled liquid crystal panel 7 willbe described in detail below. FIG. 4 is an exploded perspective view ofthe polarization-controlled liquid crystal panel 7. FIG. 5 is a planview of the polarization-controlled liquid crystal panel 7. FIG. 6 is asectional view of the polarization-controlled liquid crystal panel 7taken along the line VI-VI of FIG. 5.

The polarization-controlled liquid crystal panel 7 includes a bottomsubstrate 71 and a top substrate 72, which are made oflight-transmissive glass, quarts, or the like, and a liquid crystallayer 73 held between the bottom substrate 71 and the top substrate 72.The liquid crystal layer 73 includes, for example, twisted-nematic (TN)liquid crystal or the like. On the surface of the bottom substrate 71facing the liquid crystal layer 73, bottom electrodes 81 and 82 made oftransparent electrically-conductive films such as ITO, and an alignmentfilm 74 for regulating the initial alignment of the liquid crystal layer73 are disposed. On the surface of the top substrate 72 facing theliquid crystal layer 73, top electrodes 83 and 84 made of transparentelectrically-conductive films such as ITO, and an alignment film 75 forregulating the initial alignment of the liquid crystal layer 73 aredisposed.

As shown in FIG. 4, the bottom electrodes 81 and 82 are comb-likeelectrodes having connecting portions 81 b and 82 b and pluralities ofstrip electrodes 81 a and 82 a. Viewed from the F direction and adirection orthogonal to the G direction, the connecting portions 81 band 82 b are disposed in areas that are outside a portion of the bottomsubstrate 71 corresponding to a pixel area 2 c of the display panel 2 inwhich the pixels are disposed and that are along two sides of the bottomsubstrate 71 parallel to the G direction. The strip electrodes 81 a and82 a extend, parallel to the F direction, from the connecting portions81 b and 82 b inward of the bottom substrate 71 in a comb-like manner.

Viewed from the F direction and a direction orthogonal to the Gdirection, the strip electrodes 81 a and 82 a are formed so as tolongitudinally (in the F direction) penetrate the portion of the bottomsubstrate 71 corresponding to the pixel area 2 c of the display panel 2.Viewed from the F direction and a direction orthogonal to the Gdirection, the strip electrodes 81 a and 82 a are arranged in the widthdirection (G direction) at pitch 2W, which is twice the pitch W at whichthe unit areas 7 c are arranged, throughout the portion of the bottomsubstrate 71 corresponding to the pixel area 2 c of the display panel 2.The bottom electrodes 81 and 82 are arranged so that the stripelectrodes 81 a and 82 a serving as the teeth of the combs interlock oneanother but do not overlap one another.

That is, the strip electrodes 81 a and 82 a extending in the F directionare alternately arranged at pitch W in the G direction in the portion ofthe bottom substrate 71 corresponding to the pixel area 2 c of thedisplay panel 2.

The top electrodes 83 and 84 are comb-like electrodes having connectingportions 83 b and 84 b and pluralities of strip electrodes 83 a and 84a. Viewed from the F direction and a direction orthogonal to the Gdirection, the connecting portions 83 b and 84 b are disposed in areasthat are outside a portion of the top substrate 72 corresponding to thepixel area 2 c of the display panel 2 in which the pixels are disposedand that are along two sides of the top substrate 72 parallel to the Gdirection. The strip electrodes 83 a and 84 a extend, parallel to the Fdirection, from the connecting portions 83 b and 84 b inward of the topsubstrate 72 in a comb-like manner.

Viewed from the F direction and a direction orthogonal to the Gdirection, the strip electrodes 83 a and 84 a are formed so as tolongitudinally (in the F direction) penetrate the portion of the topsubstrate 72 corresponding to the pixel area 2 c of the display panel 2.Viewed from the F direction and a direction orthogonal to the Gdirection, the strip electrodes 83 a and 84 a are arranged in thebreadthwise direction (G direction) at pitch 4W, which is four times thepitch W at which the unit areas 7 c are arranged, throughout the portionof the top substrate 72 corresponding to the pixel area 2 c of thedisplay panel 2. The top electrodes 83 and 84 are arranged so that thestrip electrodes 83 a and 84 a serving as the teeth of the combsinterlock one another but do not overlap one another.

That is, the strip electrodes 83 a and 84 a extending in the F directionare alternately arranged at pitch 2W, which is twice the pitch W atwhich the strip electrodes 81 a and 82 a are arranged, in the portion ofthe top substrate 72 corresponding to the pixel area 2 c of the displaypanel 2.

As shown in FIG. 5, when the polarization-controlled liquid crystalpanel 7 is in an assembled state, viewed from the F direction and adirection orthogonal to the G direction, the top electrode 83 is formedso that the longitudinal centerline of each of the strip electrodes 83 asubstantially coincides with the midline between the longitudinalcenterlines of the strip electrodes 81 a and 82 a of the bottomelectrodes 81 (area hatched with upward-sloping broken lines in FIG. 5)and 82 (area hatched with downward-sloping broken lines in FIG. 5).Similarly, the longitudinal centerline of each of the strip electrodes84 a of the top electrode 84 substantially coincides with the midlinebetween the longitudinal centerlines of the strip electrodes 81 a and 82a of the bottom electrodes 81 and 82. The short-side width of each ofthe strip electrodes 83 a and 84 a of the top electrodes 83 and 84substantially coincides with the combined widths of the strip electrodes81 a and 82 a of the bottom electrodes 81 and 82. Therefore, when thepolarization-controlled liquid crystal panel 7 is in its assembledstate, viewed from the F direction and a direction orthogonal to the Gdirection, a pair of the strip electrodes 81 a and 82 a of the bottomelectrodes 81 and 82 is superposed on each of the strip electrodes 83 aand 84 a of the top electrodes 83 and 84.

The unit areas 7 c of the polarization-controlled liquid crystal panel 7shown in FIG. 3 correspond to areas where the strip electrodes 81 a ofthe bottom electrode 81 and 82 or the strip electrodes 82 a of thebottom electrode 82 are superposed on the strip electrodes 83 a of thetop electrode 83 or the strip electrodes 84 a of the top electrode 84.In other words, the alignment of the liquid crystal layer 73 isdetermined by potential differences in portions where the stripelectrodes 81 a or 82 a face the strip electrodes 83 a or 84 a, therebyforming the polarization-controlled areas 7 a and 7 b of thepolarization-controlled liquid crystal panel 7.

In the first embodiment, when a sufficient potential difference isapplied between the bottom electrodes 81 and 82 and the top electrodes83 and 84 in one unit area 7 c, this unit area 7 c becomes thepolarization-controlled area 7 a for allowing light with the firstpolarization axis to pass through. When no sufficient potentialdifference is generated between the bottom electrodes 81 and 82 and thetop electrodes 83 and 84, this unit area 7 c becomes thepolarization-controlled area 7 b for changing light from having thefirst polarization axis to having the second polarization axissubstantially orthogonal to the first polarization axis.

The potential difference between the bottom electrodes 81 and 82 and thetop electrodes 83 and 84 is determined by voltages applied to electrodesfacing one another. The voltages applied to the electrodes arecontrolled by the drive circuit 100, which will be described below. FIG.7 is an electrical circuit diagram of the drive circuit 100.

The drive circuit 100 includes an oscillation circuit 110, a frequencydividing circuit 120, AND circuits 101 to 104, XOR circuits 105 and 106,a NAND circuit 107, and switches 131 to 134. Output ends OUT1 to OUT4are connected to the bottom electrodes 81 and 82 and the top electrodes83 and 84, respectively.

The switches 132, 133, and 134 each have two (first and second) inputends, which are connected to supply voltage 5V and to ground potentialGND, respectively. An output end of the switch 132 is connected to two(first and second) input ends of the NAND circuit 107 and a first inputend of the XOR circuit 105. An output end of the switch 133 is connectedto the oscillation circuit 110. An output end of the switch 134 isconnected to the frequency dividing circuit 120 and to first input endsof the circuits 101 to 104. An output end of the switch 131 is connectedto a second input end of the AND circuit 101 and a second input end ofthe XOR circuit 105.

The switches 131 to 134 are switched so that the output ends thereof areselectively connected to one of two (first and second) input endsthereof on the basis of a switching signal from the controller 30.

The oscillation circuit 110 is a CR oscillation circuit and has NANDcircuits 111 to 113, a capacitor 115, resistors 116 and 117, and aswitch 118. By supplying the supply voltage 5V from the switch 133 tothe NAND circuit 111, the oscillation circuit 110 outputs a clock signalV0.

The frequency of the clock signal V0 output from the oscillation circuit110 is selected from two different frequencies determined by theresistances of the resistors 116 and 117 depending on whether the switch118 is connected to the resistor 116 or the resistor 117. The switch 118is switched so that the switch 118 is connected to one of the tworesistors 116 and 117 on the basis of a switching signal from thecontroller 30.

The frequency dividing circuit 120 has two D-type flip flops(hereinafter referred to as “DFFs”) 121 and 122. Of the first DFF 121, aclock input terminal CK1 is connected to the output of the oscillationcircuit 110, and a non-inverted output terminal QB1 is connected to aninput terminal D1. The first DFF 121 outputs, from an output terminalQ1, a clock signal V1 at a frequency half the frequency of the clocksignal V0 input from the oscillation circuit 110. The first DFF 121divides the frequency of the clock signal V0 by two to obtain the clocksignal V1 having a rectangular wave with a duty ratio of 50%.

Of the second DFF 122, a clock input terminal CK2 is connected to theoutput terminal Q1 of the first DFF 121, and a non-inverted outputterminal QB2 is connected to an input terminal D2. The second DFF 122outputs, from an output terminal Q2, a clock signal V2 at a frequencyhalf the frequency of the clock signal V1 input from the first DFF 121.

The output terminal Q1 of the first DFF 121 is connected to the firstinput end of the switch 131, a first input end of the XOR circuit 106,and a second input end of the AND circuit 103. The output terminal Q2 ofthe second DFF 122 is connected to the second input end of the switch131.

An output end of the NAND circuit 107 is connected to a second input endof the XOR circuit 106. Output ends of the XOR circuits 105 and 106 areconnected to second input ends of the AND circuits 102 and 104,respectively.

Output ends of the four AND circuits 101 to 104 are connected to theoutput ends OUT1 to OUT4, respectively. The output ends OUT1 to OUT4 areconnected to the bottom electrodes 81 and 82 and the top electrodes 83and 84, respectively. Clock signals output from the AND circuits 101 to104 are output to the bottom electrodes 81 and 82 and the top electrodes83 and 84, respectively.

The operation of the drive circuit 100 and the waveforms of voltagesoutput from the drive circuit 100 to the bottom electrodes 81 and 82 andthe top electrodes 83 and 84 will be described. FIGS. 8A to 8C aretiming charts for describing voltages output from the output ends OUT1to OUT4.

In the dual-screen display mode, on the basis of a switching signal fromthe controller 30, an input end of the switch 118 is connected to theresistor 116, the input end of the switch 131 is connected to the outputterminal Q1 of the first DFF 121, and the input end of the switch 132 isconnected to the ground potential GND. The input ends of the switches133 and 134 are connected to the supply voltage 5V. Therefore, as shownin FIG. 8A, the output ends OUT1, OUT2, and OUT3 output the clock signalV1 output from the output terminal Q1 of the first DFF 121, whereas theoutput end OUT4 outputs an inverted signal of the clock signal V1, whichis inverted by the XOR circuit 106.

That is, the drive circuit 100 applies voltages to the top electrodes 83and 84 so that the adjacent strip electrodes 83 a and 84 a of the topelectrodes 83 and 84 have opposite phases, and the drive circuit 100applies, to the bottom electrodes 81 and 82, a voltage having the samephase as one of the voltages applied to the top electrodes 83 and 84.Therefore, a potential difference is generated between the top electrode84 and the bottom electrodes 81 and 82 facing the top electrode 84, and,the polarization-controlled areas 7 a and 7 b are alternately formedevery two unit areas 7 c of the polarization-controlled liquid crystalpanel 7.

In the three-dimensional image display mode, on the basis of a switchingsignal from the controller 30, the input end of the switch 118 isconnected to the resistor 116, the input end of the switch 131 isconnected to the output terminal Q1 of the first DFF 121, and the inputend of the switch 132 is connected to the supply voltage 5V. The inputends of the switches 133 and 134 are connected to the supply voltage 5V.Therefore, as shown in FIG. 8B, the output ends OUT1, OUT3, and OUT4output the clock signal V1 output from the output terminal Q1 of thefirst DFF 121, whereas the output end OUT2 outputs an inverted signal ofthe clock signal V1, which is inverted by the XOR circuit 105.

That is, the drive circuit 100 applies voltages to the bottom electrodes81 and 82 so that the adjacent strip electrodes 81 a and 82 a of thebottom electrodes 81 and 82 have opposite phases, and the drive circuit100 applies, to the top electrodes 83 and 84, a voltage having the samephase as one of the voltages applied to the bottom electrodes 81 and 82.Therefore, a potential difference is generated between the bottomelectrode 82 and the top electrodes 83 and 84 facing the bottomelectrode 82, and, the polarization-controlled areas 7 a and 7 b arealternately formed every unit area 7 c of the polarization-controlledliquid crystal panel 7.

In the two-dimensional image display mode, on the basis of a switchingsignal from the controller 30, the input end of the switch 118 isconnected to the resistor 117, the input end of the switch 131 isconnected to the output terminal Q2 of the second DFF 122, and the inputend of the switch 132 is connected to the supply voltage 5V. The inputends of the switches 133 and 134 are connected to the supply voltage 5V.Therefore, as shown in FIG. 8C, the output ends OUT3 and OUT4 output theclock signal V1 output from the output terminal Q1 of the first DFF 121.The output end OUT1 outputs the clock signal V2 output from the outputterminal Q2 of the second DFF 122. The output end OUT2 outputs aninverted signal of the clock signal V2, which is inverted by the XORcircuit 105.

That is, the drive circuit 100 applies voltages to the bottom electrodes81 and 82 so that the adjacent strip electrodes 81 a and 82 a of thebottom electrodes 81 and 82 have opposite phases, and the drive circuit100 applies, to the top electrodes 83 and 84, voltages having a periodhalf that of the voltages applied to the bottom electrodes 81 and 82.Therefore, a potential difference is alternately and periodicallygenerated between the bottom electrode 81 and the top electrodes 83 and84 and between the bottom electrode 82 and the top electrodes 83 and 84.Thus, the polarization-controlled areas 7 a and 7 b are alternatelyformed every unit area 7 c of the polarization-controlled liquid crystalpanel 7, and the polarization-controlled areas 7 a and 7 b areperiodically and alternately switched. The period during which thepolarization-controlled areas 7 a and 7 b are switched is four times theperiod of the clock signal V0 determined by the resistor 117 of theoscillation circuit 110 and is 1/60 seconds in the first embodiment.

Next, the operation of the image display device 1 of the firstembodiment will be described in detail.

Dual-Screen Display Mode

With reference to FIGS. 2 and 9 to 11, the operation of the imagedisplay device 1 of the first embodiment in the dual-screen display modewill be described. FIG. 11 is a diagram for describing areas of thedisplay panel viewed by the viewers in the dual-screen display mode ofthe image display device of the first embodiment shown in FIG. 1.

Image data including information about two different images is inputfrom an external device to the controller 30. At the same time, theexternal device gives an image display mode switching command to thecontroller 30. By supplying image signals from the controller 30 to thedisplay panel 2, images are displayed on the display panel 2. The imagesignals supplied from the controller 30 are two image signals for animage L2 (e.g., a television image) and an image R2 (e.g., a carnavigation image). In the first embodiment, as shown in FIG. 10, in thedual-screen display mode, the image L2 is displayed in the pixel rows 2a of the display panel 2, and the image R2 is displayed in the pixelrows 2 b of the display panel 2.

With reference to FIGS. 2 and 10, the structure of thepolarization-controlled liquid crystal panel 7 and the display panel 2for providing different images to the viewers 10 and 20 at differentviewing positions will be described. In the image display device 1 inthe dual-screen display mode, as shown in FIG. 2, a pair of thepolarization-controlled areas 7 a and 7 b of the polarization-controlledliquid crystal panel 7 is provided for each of the lens portions 8 a ofthe lenticular lens 8. That is, in the dual-screen display mode, as hasbeen described above, the polarization-controlled areas 7 a and 7 b ofthe polarization-controlled liquid crystal panel 7 each include two unitareas 7 c (see FIG. 3).

With this structure, light emitted from the backlight 5 is routed to thepolarization plate 6, which is disposed on the side of the backlight 5facing the viewers 10 and 20, and only light with the first polarizationaxis is allowed to pass through the polarization plate 6 toward thepolarization-controlled liquid crystal panel 7. The light with the firstpolarization axis passes through the polarization-controlled areas 7 aand 7 b of the polarization-controlled liquid crystal panel 7. In thiscase, the light entering the polarization-controlled areas 7 a of thepolarization-controlled liquid crystal panel 7 is allowed to passthrough the polarization-controlled areas 7 a without changing thepolarization axis. In contrast, the polarization axis of the lightentering the polarization-controlled areas 7 b of thepolarization-controlled liquid crystal panel 7 is changed substantiallyby 90 degrees, and the light with the second polarization axis exitsfrom the polarization-controlled areas 7 b. Thereafter, as shown in FIG.2, the light with the first polarization axis, which comes from thepolarization-controlled areas 7 a, is collected by the lenticular lens 8so that the light is directed to the viewer 10. The light with thesecond polarization axis substantially orthogonal to the firstpolarization axis, which comes from the polarization-controlled areas 7b, is collected by the lenticular lens 8 so that the light is directedto the viewer 20.

As shown in FIG. 10, the light with the first polarization axis, whichis directed to the viewer 10, enters the retardation film 9 having thetransmissive areas 9 a and the polarization areas 9 b. The light withthe first polarization axis passes through the transmissive areas 9 aand the polarization areas 9 b of the retardation film 9. In this case,the light passing through the transmissive areas 9 a of the retardationfilm 9 is allowed to pass through the transmissive areas 9 a withoutchanging the polarization axis. In contrast, the polarization axis ofthe light entering the polarization areas 9 b is changed substantiallyby 90 degrees, and the light with the second polarization axis exitsfrom the polarization areas 9 b. Thereafter, the light with the firstpolarization axis, which comes from the transmissive areas 9 a of theretardation film 9 and which is directed to the viewer 10, enters thepolarization plate 4 disposed between the display panel 2 and theretardation film 9, passes through the polarization plate 4, and entersthe pixel rows 2 a of the display panel 2. In contrast, the light withthe second polarization axis substantially orthogonal to the firstpolarization axis, which comes from the polarization areas 9 b of theretardation film 9 and which is directed to the viewer 10, enters thepolarization plate 4 disposed between the display panel 2 and theretardation film 9 and is absorbed by the polarization plate 4. Thus, nolight passing through the pixel rows 2 b of the display panel 2displaying the image R2 reaches the viewer 10, and the viewer 10 cannotsee the image R2 displayed in the pixel rows 2 b of the display panel 2.Accordingly, the viewer 10 can see only the image L2 displayed in thepixel rows 2 a of the display panel 2, as shown in FIG. 11.

As shown in FIG. 10, the light with the second polarization axis, whichis directed to the viewer 20, enters the retardation film 9 having thetransmissive areas 9 a and the polarization areas 9 b. The light withthe second polarization axis substantially orthogonal to the firstpolarization axis passes through the transmissive areas 9 a and thepolarization areas 9 b of the retardation film 9. In this case, thelight passing through the transmissive areas 9 a of the retardation film9 is allowed to pass through the transmissive areas 9 a without changingthe polarization axis. In contrast, the polarization axis of the lightentering the polarization areas 9 b is changed substantially by 90degrees, and the light with the first polarization axis exits from thepolarization areas 9 b. Thereafter, the light with the secondpolarization axis substantially orthogonal to the first polarizationaxis, which comes from the transmissive areas 9 a of the retardationfilm 9 and which is directed to the viewer 20, enters the polarizationplate 4 disposed between the display panel 2 and the retardation film 9and is absorbed by the polarization plate 4. Thus, no light passingthrough the pixel rows 2 a of the display panel 2 displaying the imageL2 reaches the viewer 20, and the viewer 20 cannot see the image L2displayed in the pixel rows 2 a of the display panel 2. In contrast, thelight with the first polarization axis, which comes from thepolarization areas 9 b of the retardation film 9 and which is directedto the viewer 20, enters the polarization plate 4 disposed between thedisplay panel 2 and the retardation film 9, passes through thepolarization plate 4, and enters the pixel rows 2 b of the display panel2. Accordingly, the viewer 20 can see only the image R2 displayed in thepixel rows 2 b of the display panel 2, as shown in FIG. 11,

Three-Dimensional Image Display Mode

Next, the operation of the image display device 1 of the firstembodiment in the three-dimensional image display mode will be describedwith reference to FIGS. 12 to 14. FIG. 12 is a view of the display panelviewed from the top by the viewers for describing the principle. Ofdisplaying a three-dimensional image by the image display device of thefirst embodiment shown in FIG. 1. FIG. 13 is an exploded perspectiveview of the image display device for describing the principle ofdisplaying a three-dimensional image by the image display device. FIG.14 is a diagram for describing areas of the display panel viewed by theviewers in the three-dimensional image display mode of the image displaydevice.

Image data including information about two different images is inputfrom an external device to the controller 30. At the same time, theexternal device gives an image display mode switching command to thecontroller 30. By supplying image signals from the controller 30 to thedisplay panel 2, images are displayed on the display panel 2. The imagesignals supplied from the controller 30 are two image signals for aleft-eye image L3 entering the left eyes 10 a and 20 a of the viewers 10and 20 and a right-eye image R3 entering the right eyes 10 b and 20 b ofthe viewers 10 and 20. In the first embodiment, as shown in FIG. 13, inthe three-dimensional image display mode, the left-eye image L3 isdisplayed in the pixel rows 2 a of the display panel 2, and theright-eye image R3 is displayed in the pixel rows 2 b of the displaypanel 2.

The structure of the polarization-controlled liquid crystal panel 7 andthe display panel 2 for providing a three-dimensional image to theviewers 10 and 20 at different viewing positions will be described. Asshown in FIG. 12, two pairs of the polarization-controlled areas 7 a and7 b of the polarization-controlled liquid crystal panel 7 are providedfor each of the lens portions 8 a of the lenticular lens 8. That is, inthe three-dimensional image display mode, as has been described above,the polarization-controlled areas 7 a and 7 b of thepolarization-controlled liquid crystal panel 7 each include one unitarea 7 c (see FIG. 3).

With this structure, light emitted from the backlight 5 is routed to thepolarization plate 6, which is disposed on the side of the backlight 5facing the viewers 10 and 20, and only light with the first polarizationaxis is allowed to pass through the polarization plate 6 toward thepolarization-controlled liquid crystal panel 7. The light with the firstpolarization axis passes through the polarization-controlled areas 7 aand 7 b of the polarization-controlled liquid crystal panel 7. In thiscase, the light entering the polarization-controlled areas 7 a of thepolarization-controlled liquid crystal panel 7 is allowed to passthrough the polarization-controlled areas 7 a without changing thepolarization axis. In contrast, the polarization axis of the lightentering the polarization-controlled areas 7 b of thepolarization-controlled liquid crystal panel 7 is changed substantiallyby 90 degrees, and the light with the second polarization axis exitsfrom the polarization-controlled areas 7 b. Thereafter, the light withthe first polarization axis, which comes from thepolarization-controlled areas 7 a, is collected by the lenticular lens 8so that the light is directed to the left eyes 10 a and 20 a of theviewers 10 and 20. The light with the second polarization axissubstantially orthogonal to the first polarization axis, which comesfrom the polarization-controlled areas 7 b, is collected by thelenticular lens 8 so that the light is directed to the right eyes 10 band 20 b of the viewers 10 and 20.

As shown in FIG. 13, the light with the first polarization axis, whichis directed to the left eyes 10 a and 20 a of the viewers 10 and 20,enters the retardation film 9 having the transmissive areas 9 a and thepolarization areas 9 b. The light with the first polarization axispasses through the transmissive areas 9 a and the polarization areas 9 bof the retardation film 9. In this case, the light passing through thetransmissive areas 9 a of the retardation film 9 is allowed to passthrough the transmissive areas 9 a without changing the polarizationaxis. In contrast, the polarization axis of the light entering thepolarization areas 9 b is changed substantially by 90 degrees, and thelight with the second polarization axis exits from the polarizationareas 9 b. Thereafter, the light with the first polarization axis, whichcomes from the transmissive areas 9 a of the retardation film 9 andwhich is directed to the left eyes 10 a and 20 a of the viewers 10 and20, enters the polarization plate 4 disposed between the display panel 2and the retardation film 9, passes through the polarization plate 4, andenters the pixel rows 2 a of the display panel 2. In contrast, the lightwith the second polarization axis substantially orthogonal to the firstpolarization axis, which comes from the polarization areas 9 b of theretardation film 9 and which is directed to the left eyes 10 a and 20 aof the viewers 10 and 20, enters the polarization plate 4 disposedbetween the display panel 2 and the retardation film 9 and is absorbedby the polarization plate 4. Thus, no light passing through the pixelrows 2 b of the display panel 2 displaying the right-eye image R3reaches the left eyes 10 a and 20 a of the viewers 10 and 20, and theleft eyes 10 a and 20 a of the viewers 10 and 20 cannot see theright-eye image R3 displayed in the pixel rows 2 b of the display panel2. Accordingly, only the left-eye image L3 displayed in the pixel rows 2a of the display panel 2 enters the left eyes 10 a and 20 a of theviewers 10 and 20, as shown in FIG. 14.

As shown in FIG. 13, the light with the second polarization axis, whichis directed to the right eyes 10 b and 20 b of the viewers 10 and 20,enters the retardation film 9 having the transmissive areas 9 a and thepolarization areas 9 b. The light with the second polarization axispasses through the transmissive areas 9 a and the polarization areas 9 bof the retardation film 9. In this case, the light passing through thetransmissive areas 9 a of the retardation film 9 is allowed to passthrough the transmissive areas 9 a without changing the polarizationaxis. In contrast, the polarization axis of the light entering thepolarization areas 9 b is changed substantially by 90 degrees, and thelight with the first polarization axis exits from the polarization areas9 b. Thereafter, the light with the second polarization axis, whichcomes from the transmissive areas 9 a of the retardation film 9 andwhich is directed to the right eyes 10 b and 20 b of the viewers 10 and20, enters the polarization plate 4 disposed between the display panel 2and the retardation film 9 and is absorbed by the polarization plate 4.Thus, no light passing through the pixel rows 2 a of the display panel 2displaying the left-eye image L3 reaches the right eyes 10 b and 20 b ofthe viewers 10 and 20, and the right eyes 10 b and 20 b of the viewers10 and 20 cannot see the left-eye image L3 displayed in the pixel rows 2a of the display panel 2. In contrast, the light with the firstpolarization axis, which comes from the polarization areas 9 b of theretardation film 9 and which is directed to the right eyes 10 b and 20 bof the viewers 10 and 20, enters the polarization plate 4 disposedbetween the display panel 2 and the retardation film 9, passes throughthe polarization plate 4, and enters the pixel rows 2 b of the displaypanel 2. Accordingly, the right-eye image R3 displayed in the pixel rows2 b of the display panel 2 enters the right eyes 10 b and 20 b of theviewers 10 and 20, as shown in FIG. 14. As has been described above, theleft-eye image L3 and the right-eye image R3 having binocular parallaxenter the left and right eyes of the viewers 10 and 20, respectively,and hence, the viewers 10 and 20 can see a three-dimensional image.

Two-Dimensional Image Display Mode with Less Image Deterioration

Next, the operation of the image display device 1 of the firstembodiment in the two-dimensional image display mode will be describedwith reference to FIGS. 12, 15, and 16. FIG. 15 is a diagram showing thepolarization-controlled liquid crystal panel, the retardation film, andthe display panel in the two-dimensional image display mode of the imagedisplay device. FIG. 16 is a diagram describing areas of the displaypanel viewed by the viewers in the two-dimensional image display mode ofthe image display device.

Image data is input from an external device to the controller 30. At thesame time, the external device gives an image display mode switchingcommand to the controller 30. As shown in FIG. 15, in thetwo-dimensional image display mode, a two-dimensional image S1 isdisplayed on the display panel 2 from 0/120 seconds to 2/120 seconds,and a two-dimensional image S2 is displayed from 2/120 seconds to 4/120seconds. The two-dimensional images S1 and S2 are sequentially andalternately displayed every 1/60 seconds.

The structure of the polarization-controlled liquid crystal panel 7 andthe display panel 2 for providing a two-dimensional image to the viewers10 and 20 at different viewing positions will be described. Two pairs ofthe polarization-controlled areas 7 a and 7 b of thepolarization-controlled liquid crystal panel 7 are provided for each ofthe lens portions 8 a of the lenticular lens 8, as in thethree-dimensional image display mode shown in FIG. 12. That is, in thetwo-dimensional image display mode with less image deterioration, thepolarization-controlled areas 7 a and 7 b of the polarization-controlledliquid crystal panel 7 each include one unit area 7 c (see FIG. 3).

In the two-dimensional image display mode, the polarization-controlledliquid crystal panel 7 is controlled so that the polarization-controlledareas 7 a and 7 b of the polarization-controlled liquid crystal panel 7are switched every 1/2 frame period of the display panel 2 (every 1/120seconds) with the above-described structure, as shown in FIGS. 15 and16, from 0/120 seconds to 1/120 seconds, the two-dimensional image S1displayed in the pixel rows 2 a of the display panel 2 enters the lefteyes 10 a and 20 a of the viewers 10 and 20, and the two-dimensionalimage S1 displayed in the pixel rows 2 b of the display panel 2 entersthe right eyes 10 b and 20 b of the viewers 10 and 20. From 1/120seconds to 2/120 seconds, the polarization-controlled areas 7 a and 7 bof the polarization-controlled liquid crystal panel 7 are controlled sothat the polarization-controlled areas 7 a and 7 b are switched. Thus,light directed to the left eyes 10 a and 20 a of the viewers 10 and 20passes through the polarization-controlled areas 7 b of thepolarization-controlled liquid crystal panel 7, the polarization axis ofwhich is changed substantially by 90 degrees, and the light with thechanged polarization axis is routed toward the retardation film 9.Therefore, as shown in FIG. 16, from 1/120 seconds to 2/120 seconds, thetwo-dimensional image S1 displayed in the pixel rows 2 b of the displaypanel 2 enters the left eyes 10 a and 20 a of the viewers 10 and 20, andthe two-dimensional image S1 displayed in the pixel rows 2 a of thedisplay panel 2 enters the right eyes 10 b and 20 b of the viewers 10and 20.

From 2/120 seconds to 3/120 seconds, as in the interval from 0/120seconds to 1/120 seconds, the two-dimensional image S2 displayed in thepixel rows 2 a of the display panel 2 enters the left eyes 10 a and 20 aof the viewers 10 and 20, and the two-dimensional image S2 displayed inthe pixel rows 2 b of the display panel 2 enters the right eyes 10 b and20 b of the viewers 10 and 20. From 3/120 seconds to 4/120 seconds, asin the interval from 1/120 seconds to 2/120 seconds, the two-dimensionalimage S2 displayed in the pixel rows 2 b of the display panel 2 entersthe left eyes 10 a and 20 a of the viewers 10 and 20, and thetwo-dimensional image S2 displayed in the pixel rows 2 a of the displaypanel 2 enters the right eyes 10 b and 20 b of the viewers 10 and 20. Inthis manner, a two-dimensional image S displayed in the entire displaypanel 2 enters the left and right eyes of the viewers 10 and 20 within2/120 seconds (1/60 seconds). Accordingly, a two-dimensional image withless deterioration can be provided to the viewers 10 and 20.

The image display device of the first embodiment described above has thefollowing advantages.

Between the backlight 5 and the display panel 2, thepolarization-controlled liquid crystal panel 7 is disposed to separatelight emitted from the backlight 5 through the polarization plate 6 intoa light beam with the first polarization axis and a light beam with thesecond polarization axis substantially orthogonal to the firstpolarization axis. Between the polarization-controlled liquid crystalpanel 7 and the display panel 2, the lenticular lens 8 is provided toroute the light beams with different polarization axes, which areseparated by the polarization-controlled liquid crystal panel 71 inpredetermined directions. Accordingly, the light emitted from thebacklight 5 can be separated, before entering the display panel 2, intolight beams directed to the viewers 10 and 20 at different viewingpositions. Even when a high-resolution display panel 2 with a smallpixel pitch is used, the light is directed to the viewers 10 and 20regardless of the pixel pitch of the display panel 2. Therefore, ahigh-resolution image can be provided to the viewers 10 and 20 atdifferent viewing positions.

Because the lenticular lens 8 is provided to direct the light beams withdifferent polarization axes, which are separated by thepolarization-controlled liquid crystal panel 7, in predeterminedassociated directions, the light beams directed to the viewers 10 and 20are not blocked, unlike the case where the light coming from the displaypanel 2 is directed to pass through a member that restricts the light tobe routed in directions with predetermined angles. Therefore, theluminance of light directed to the viewers 10 and 20 is prevented fromdecreasing, and hence an image is prevented from being displayed as adark image.

The polarization-controlled liquid crystal panel 7 is provided with thepolarization-controlled areas 7 a for allowing light with the firstpolarization axis to pass through, and the polarization-controlled areas7 b for changing light from having the first polarization axis to havingthe second polarization axis substantially orthogonal to the firstpolarization axis. The lenticular lens 8 is provided with thesubstantially semi-cylindrical lens portions 8 a each of which isassociated with a pair of the polarization-controlled areas 7 a and 7 b.Hence, light with the first polarization axis and light with the secondpolarization axis substantially orthogonal to the first polarizationaxis are separately directed by the lens portions 8 a of the lenticularlens 8 to the viewers 10 and 20 at different viewing positions.Therefore, different images can be easily provided to the viewers 10 and20 at different viewing positions.

Since the display panel 2 is provided with the pixel rows 2 a and 2 b inassociation with the transmissive areas 9 a and the polarization areas 9b of the retardation film 91 which extend in the G direction of FIG. 1,light passing through the transmissive areas 9 a of the retardation film9 can be directed to enter the pixel rows 2 a of the display panel 2 andto be routed to the viewer 10 while maintaining the image L2 beingdisplayed in the pixel rows 2 a of the display panel 2 (see FIG. 9).Also, light passing through the polarization areas 9 b can be directedto enter the pixel rows 2 b of the display panel 2 and to be routed tothe viewer 20 while maintaining the image R2 being displayed in thepixel rows 2 a of the display panel 2 (see FIG. 9). Accordingly,different images can be provided to the viewers 10 and 20 at differentviewing positions.

By controlling the voltages applied to the bottom electrodes 81 and 82and the top electrodes 83 and 84 of the polarization-controlled liquidcrystal panel 7, the polarization-controlled areas 7 a for allowinglight with the first polarization axis to pass through and thepolarization-controlled areas 7 b for changing light from having thefirst polarization axis to having the second polarization axissubstantially orthogonal to the first polarization axis can be easilyformed on the polarization-controlled liquid crystal panel 7. Therefore,the polarization axis of light emitted from the backlight 5 can beeasily controlled. Accordingly, light emitted from the backlight 5 isdirected through the segmented polarization-controlled areas 7 a and 7 bto enter the lens portions 8 a of the lenticular lens 8, therebybreaking a light-reaching area into segments. Since the light-reachingarea can be broken into segments corresponding to the right eye 10 b (20b) and the left eye 10 a (20 a) of the viewer 10 (20), images havingbinocular parallax can be directed to enter the left eye 10 a (20 a) andthe right eye 10 b (20 b) of the viewer 10 (20). Accordingly, athree-dimensional image can be provided to the viewers 10 and 20 atdifferent viewing positions.

The bottom electrodes 81 and 82 of the polarization-controlled liquidcrystal panel 7 have comb-like shapes, and the bottom electrodes 81 and82 are disposed on the bottom substrate 71 so that the strip electrodes81 a and 82 a interlock one another. Similarly, the top electrodes 83and 84 have comb-like shapes, and the top electrodes 83 and 84 aredisposed on the top substrate 72 so that the strip electrodes 83 a and84 a interlock one another. Therefore, two electrodes to which differentvoltages are applied can be fabricated using a singleelectrically-conductive layer on each substrate, and hence thepolarization-controlled liquid crystal panel 7 can be easily fabricated.The pitch at which the strip electrodes are arranged can be easilyreduced.

Since the drive circuit 100 for controlling the polarization-controlledliquid crystal panel 7 includes a combination of a simple knownelectrical circuit including the oscillation circuit 110, the frequencydividing circuit 120, and a logic circuit, the drive circuit 100 can beeasily fabricated.

Next, a specific example of an electronic apparatus to which the imagedisplay device of the first embodiment is applicable will be describedwith reference to FIG. 17.

The case where the image display device of the first embodiment isapplied to a display unit of a cellular phone will be described. FIG. 17is a perspective view of the structure of the cellular phone. As shownin FIG. 17, a cellular phone 200 includes a plurality of operationbuttons 201, an earpiece 202, a mouthpiece 203, and a display unit 204to which the image display device of the first embodiment is applied.

Electronic apparatuses to which the image display device of the firstembodiment is applicable include, besides the cellular phone shown inFIG. 17, a personal computer, a liquid crystal television, aviewfinder-/monitor-direct-view-type video tape recorder, a carnavigation apparatus, a pager, an electronic notebook, an electroniccalculator, a word-processor, a workstation, a videophone, apoint-of-sale (POS) terminal, a digital still camera, or the like.

Second Embodiment

A second embodiment of the invention will be described with reference toFIGS. 18 and 19A to 19D.

An image display device of the second embodiment differs from the imagedisplay device 1 of the first embodiment only in the structure of thedrive circuit 100. In the second embodiment, components similar to thoseof the image display device 1 of the first embodiment are given the samereference numerals, and repeated descriptions thereof will be omittedappropriately.

The image display device 1 of the second embodiment has three imagedisplay modes, namely, the dual-screen display mode in which differentimages are provided to the viewers 10 and 20 residing at differentviewing positions, the three-dimensional image display mode in which athree-dimensional image is provided to the viewers 10 and 20, and thetwo-dimensional image display mode in which one and the sametwo-dimensional image is provided to the viewers 10 and 20. By switchingamong these image display modes, the image display device 1 can provideimages in various modes. The dual-screen display mode of the secondembodiment differs from the first embodiment in that it has two modes,namely, a first dual-screen display mode in which the image L2 isprovided to the viewer 10 and simultaneously the image R2 is provided tothe viewer 20, and a second dual-screen display mode in which, incontrast to the first dual-screen display mode, the image R2 is providedto the viewer 10 and simultaneously the image L2 is provided to theviewer 20. In the second embodiment, the first and second dual-screendisplay modes are switched.

The structure and operation of a drive circuit 300 for controlling thepolarization-controlled liquid crystal panel 7 of the second embodimentwill be described. FIG. 18 is an electrical circuit diagram of thecontrol circuit, and FIGS. 19A to 19D are timing charts for describingvoltages output from output ends.

The drive circuit 300 includes the oscillation circuit 110, thefrequency dividing circuit 120, AND circuits 301 to 305, XOR circuits306 to 309, a NAND circuit 310, and switches 331 to 335. Output endsOUT1 to OUT4 are connected to the bottom electrodes 81 and 82 and thetop electrodes 83 and 84, respectively.

The switches 332, 333, 334, and 335 each have two (first and second)input ends, which are connected to supply voltage 5V and groundpotential GND, respectively. An output end of the switch 332 isconnected to two (first and second) input ends of the NAND circuit 310and a first input end of the XOR circuit 306. An output end of theswitch 333 is connected to the oscillation circuit 110. An output end ofthe switch 334 is connected to the frequency dividing circuit 120 andfirst input ends of the AND circuits 301 to 304. An output end of theswitch 335 is connected to a first input end of the AND circuit 305. Anoutput end of the switch 331 is connected to a second input end of theAND circuit 301 and a second input end of the XOR circuit 306.

The switches 331 to 335 are switched so that the output ends thereof areselectively connected to one of two (first and second) input endsthereof on the basis of a switching signal from the controller 30.

The oscillation circuit 110 is, as in the first embodiment, a CRoscillation circuit. By supplying the supply voltage 5V from the switch333 to the NAND circuit 111, the oscillation circuit 110 outputs a clocksignal V0. The frequency of the clock signal V0 output from theoscillation circuit 110 is selected from two different frequenciesdetermined by the resistances of the resistors 116 and 117 depending onwhether the switch 118 is connected to the resistor 116 or the resistor117. The switch 118 is switched so that the switch 118 is connected toone of the two resistors 116 and 117 on the basis of a switching signalfrom the controller 30.

The frequency dividing circuit 120 has, as in the first embodiment, thetwo D-type flip flops (hereinafter referred to as “DFFs”) 121 and 122.Of the first DFF 121, the clock input terminal CK1 is connected to theoutput of the oscillation circuit 110, and the non-inverted outputterminal QB1 is connected to the input terminal D1. The first DFF 121outputs, from the output terminal Q1, the clock sign V1 at a frequencyhalf the frequency of the clock signal V0 input from the oscillationcircuit 110. The first DFF 121 divides the frequency of the clock signalV0 by two to obtain the clock signal V1 having a rectangular wave with aduty ratio of 50%.

Of the second DFF 122, the clock input terminal CK2 is connected to theoutput terminal Q1 of the first DFF 121, and the non-inverted outputterminal QB2 is connected to the input terminal D2. The second DFF 122outputs, from the output terminal Q2, the clock signal V2 at a frequencyhalf the frequency of the clock signal V1 input from the first DFF 121.

The output terminal Q1 of the first DFF 121 is connected to the firstinput end of the switch 331 and first input ends of the XOR circuits 307and 308. The output terminal Q2 of the second DFF 122 is connected tothe second input end of the switch 331.

An output end of the NAND circuit 310 is connected to a second input endof the AND circuit 305 and a first input end of the XOR circuit 309. Anoutput end of the AND circuit 305 is connected to second input ends ofthe XOR circuits 307 and 309. An output end of the XOR circuit 309 isconnected to a second input end of the XOR circuit 308. Output ends ofthe XOR circuits 306 to 308 are connected to second input ends of theAND circuits 302 to 304, respectively.

Output ends of the four AND circuits 301 to 304 are connected to theoutput ends OUT1 to OUT4, respectively. The output ends OUT1 to OUT4 areconnected to the bottom electrodes 81 and 82 and the top electrodes 83and 84, respectively. Clock signals output from the AND circuits 301 to304 are output to the bottom electrodes 81 and 82 and the top electrodes83 and 84, respectively.

The operation of the drive circuit 300 and the waveforms of voltagesoutput from the drive circuit 300 to the bottom electrodes 81 and 82 andthe top electrodes 83 and 84 will be described.

In the first dual-screen display mode, on the basis of a switchingsignal from the controller 30, the input end of the switch 118 isconnected to the resistor 116, the input end of the switch 331 isconnected to the output terminal Q1 of the first DFF 121, and the inputends of the switches 332 and 335 are connected to the ground potentialGND. The input ends of the switches 333 and 334 are connected to thesupply voltage 5V. Therefore, as shown in FIG. 19A, the output endsOUT1, OUT2, and OUT3 output the clock signal V1 output from the outputterminal Q1 of the first DFF 121, whereas the output end OUT4 outputs aninverted signal of the clock signal V1, which is inverted by the XORcircuit 308.

In the second dual-screen display mode, on the basis of a switchingsignal from the controller 30, the input end of the switch 118 isconnected to the resistor 116, the input end of the switch 331 isconnected to the output terminal Q1 of the first DFF 121, and the inputend of the switch 332 is connected to the ground potential GND. Theinput ends of the switches 333, 334, and 335 are connected to the supplyvoltage 5V. Therefore, as shown in FIG. 19B, the output ends OUT1, OUT2,and OUT4 output the clock signal V1 output from the output terminal Q1of the first DFF 121, whereas the output end OUT3 outputs an invertedsignal of the clock signal V1, which is inverted by the XOR circuit 307.

That is, the drive circuit 300 applies voltages to the top electrodes 83and 84 so that the adjacent strip electrodes 83 a and 84 a of the topelectrodes 83 and 84 have opposite phases, and the drive circuit 300applies, to the bottom electrodes 81 and 82, a voltage having the samephase as one of the voltages applied to the top electrodes 83 and 84.Therefore, a potential difference is generated between the stripelectrodes 84 a and the strip electrodes 81 a and 82 a facing the stripelectrodes 84 a in the first dual-screen display mode. This is the sameas the case of the dual-screen display mode of the first embodiment. Inthe second dual-screen display mode, a potential difference is generatedbetween the strip electrodes 83 a and the strip electrodes 81 a and 82 afacing the strip electrodes 83 a. Hence, the polarization-controlledareas 7 a and 7 b are alternately formed every two unit areas 7 c of thepolarization-controlled liquid crystal panel 7. The unit areas 7 c inwhich the polarization-controlled areas 7 a and 7 b are formed areinverted in position between the first and second dual-screen displaymodes.

In the three-dimensional image display mode, on the basis of a switchingsignal from the controller 30, the input end of the switch 118 isconnected to the resistor 116, the input end of the switch 331 isconnected to the output terminal Q1 of the first DFF 121, and the inputends of the switches 332, 333, and 334 are connected to the supplyvoltage 5V. The input end of the switch 335 is connected to the groundpotential GND. Therefore, as shown in FIG. 19C, the output ends OUT1,OUT3, and OUT4 output the clock signal V1 output from the outputterminal Q1 of the first DFF 121, whereas the output end OUT2 outputs aninverted signal of the clock signal V1, which is inverted by the XORcircuit 306.

That is, the drive circuit 300 applies, as in the first embodiment,voltages to the bottom electrodes 81 and 82 so that the adjacent stripelectrodes 81 a and 82 a of the bottom electrodes 81 and 82 haveopposite phases, and the drive circuit 300 applies, to the topelectrodes 83 and 84, a voltage having the same phase as one of thevoltages applied to the bottom electrodes 81 and 82. Therefore, apotential difference is generated between the bottom electrode 82 andthe top electrodes 83 and 84 facing the bottom electrode 82, and, thepolarization-controlled areas 7 a and 7 b are alternately formed everyunit area 7 c of the polarization-controlled liquid crystal panel 7.

In the two-dimensional image display mode, on the basis of a switchingsignal from the controller 30, the input end of the switch 118 isconnected to the resistor 117, the input end of the switch 331 isconnected to the output terminal Q2 of the second DFF 122, and the inputend of the switch 332 is connected to the supply voltage 5V. The inputends of the switches 333 and 334 are connected to the supply voltage 5V.The input end of the switch 335 is connected to the ground potentialGND. Therefore, as shown in FIG. 19D, the output ends OUT3 and OUT4output the clock signal V1 output from the output terminal Q1 of thefirst DFF 121. The output end OUT1 outputs the clock signal V2 outputfrom the output terminal Q2 of the second DFF 122. The output end OUT2outputs an inverted signal of the clock signal V2, which is inverted bythe XOR circuit 306.

That is, the drive circuit 300 applies, as in the first embodiment,voltages to the bottom electrodes 81 and 82 so that the adjacent stripelectrodes 81 a and 82 a of the bottom electrodes 81 and 82 haveopposite phases, and the drive circuit 300 applies, to the topelectrodes 83 and 84, voltages having a period half that of the voltagesapplied to the bottom electrodes 81 and 82. Therefore, a potentialdifference is alternately and periodically generated between the bottomelectrode 81 and the top electrodes 83 and 84 and between the bottomelectrode 82 and the top electrodes 83 and 84. Thus, thepolarization-controlled areas 7 a and 7 b are alternately formed everyunit area 7 c of the polarization-controlled liquid crystal panel 7, andthe polarization-controlled areas 7 a and 7 b are periodically andalternatively switched. The period during which thepolarization-controlled areas 7 a and 7 b are switched is four times theperiod of the clock signal V0 determined by the resistor 117 of theoscillation circuit 110 and is 1/60 seconds in the second embodiment.

Next, the operation of the image display device 1 of the secondembodiment will be described in detail.

Since the operation of the image display device 1 of the secondembodiment is the same as that of the first embodiment except for theoperation in the second dual-screen display mode, a repeated descriptionthereof will be omitted.

First Dual-Screen Display Mode

Since the first dual-screen display mode is the same as the dual-screendisplay mode of the first embodiment, a repeated description thereof isomitted. In the first dual-screen display mode, as has been describedabove, by supplying image signals from the controller 30 to the displaypanel 2, two different images, namely, the image L2 and the image R2,are simultaneously displayed on the display panel 2. However, the lightdirected to the viewer 10 only passes through the pixel rows 2 a of thedisplay panel 2 displaying the image L2, and the light directed to theviewer 20 only passes through the pixel rows 2 b of the display panel 2displaying the image R2. Thus, only the image L2 is viewed by the viewer10, whereas only the image R2 is viewed by the viewer 20.

Second Dual-Screen Display Mode

In the second dual-screen display mode, image data supplied from theexternal device to the controller 30 is the same as that in the firstdual-screen display mode. The image signals supplied from the controller30 to the display panel 2 are the same as those in the first dual-screendisplay mode. Therefore, as shown in FIG. 10, in the second dual-screendisplay mode, the image L2 is displayed in the pixel rows 2 a of thedisplay panel 2, and the image R2 is displayed in the pixel rows 2 b ofthe display panel 2.

By giving an image display mode switching command from the externaldevice to the controller 30, the output from the drive circuit 300 isswitched, and the unit areas 7 c in which the polarization-controlledareas 7 a and 7 b of the polarization-controlled liquid crystal panel 7are formed are inverted in position from those in the first dual-screendisplay mode.

With this structure, light emitted from the backlight 5 is routed to thepolarization plate 6, which is disposed on the side of the backlight 5facing the viewers 10 and 20, and only light with the first polarizationaxis is allowed to pass through the polarization plate 6 toward thepolarization-controlled liquid crystal panel 7. The light with the firstpolarization axis passes through the polarization-controlled areas 7 aand 7 b of the polarization-controlled liquid crystal panel 7. In thiscase, the light entering the polarization-controlled areas 7 a of thepolarization-controlled liquid crystal panel 7 is allowed to passthrough the polarization-controlled areas 7 a without changing thepolarization axis. In contrast, the polarization axis of the lightentering the polarization-controlled areas 7 b of thepolarization-controlled liquid crystal panel 7 is changed substantiallyby 90 degrees, and the light with the second polarization axis exitsfrom the polarization-controlled areas 7 b. Thereafter, the light withthe first polarization axis, which comes from thepolarization-controlled areas 7 a, is collected by the lenticular lens 8so that the light is directed to the viewer 20. The light with thesecond polarization axis substantially orthogonal to the firstpolarization axis, which comes from the polarization-controlled areas 7b, is collected by the lenticular lens 8 so that the light is directedto the viewer 10. That is, the polarization axes of the light beamsdirected to the viewers 10 and 20 are switched from those in the firstdual-screen display mode.

The light with the first polarization axis, which is directed to theviewer 20, enters the retardation film 9 having the transmissive areas 9a and the polarization areas 9 b. The light with the first polarizationaxis passes through the transmissive areas 9 a and the polarizationareas 9 b of the retardation film 9. In this case, the light passingthrough the transmissive areas 9 a of the retardation film 9 is allowedto pass through the transmissive areas 9 a without changing thepolarization axis. In contrast, the polarization axis of the lightentering the polarization areas 9 b is changed substantially by 90degrees, and the light with the second polarization axis exits from thepolarization areas 9 b. Thereafter, the light with the firstpolarization axis, which comes from the transmissive areas 9 a of theretardation film 9 and which is directed to the viewer 20, enters thepolarization plate 4 disposed between the display panel 2 and theretardation film 9, passes through the polarization plate 4, and entersthe pixel rows 2 a of the display panel 2. In contrast, the light withthe second polarization axis substantially orthogonal to the firstpolarization axis, which comes from the polarization areas 9 b of theretardation film 9 and which is directed to the viewer 20, enters thepolarization plate 4 disposed between the display panel 2 and theretardation film 9 and is absorbed by the polarization plate 4. Thus, nolight passing through the pixel rows 2 b of the display panel 2displaying the image R2 reaches the viewer 20, and the viewer 20 cannotsee the image R2 displayed in the pixel rows 2 b of the display panel 2.Accordingly, the viewer 20 can see only the image L2 displayed in thepixel rows 2 a of the display panel 2.

The light with the second polarization axis, which is directed to theviewer 10, enters the retardation film 9 having the transmissive areas 9a and the polarization areas 9 b. The light with the second polarizationaxis substantially orthogonal to the first polarization axis passesthrough the transmissive areas 9 a and the polarization areas 9 b of theretardation film 9. In this case, the light passing through thetransmissive areas 9 a of the retardation film 9 is allowed to passthrough the transmissive areas 9 a without changing the polarizationaxis. In contrast, the polarization axis of the light entering thepolarization areas 9 b is changed substantially by 90 degrees, and thelight with the first polarization axis exits from the polarization areas9 b. Thereafter, the light with the second polarization axissubstantially orthogonal to the first polarization axis, which comesfrom the transmissive areas 9 a of the retardation film 9 and which isdirected to the viewer 10, enters the polarization plate 4 disposedbetween the display panel 2 and the retardation film 9 and is absorbedby the polarization plate 4. Thus, no light passing through the pixelrows 2 a of the display panel 2 displaying the image L2 reaches theviewer 10, and the viewer 10 cannot see the image L2 displayed in thepixel rows 2 a of the display panel 2. In contrast, the light with thefirst polarization axis, which comes from the polarization areas 9 b ofthe retardation film 9 and which is directed to the viewer 10, entersthe polarization plate 4 disposed between the display panel 2 and theretardation film 9, passes through the polarization plate 4, and entersthe pixel rows 2 b of the display panel 2. Accordingly, the viewer 10can see only the image R2 displayed in the pixel rows 2 b of the displaypanel 2.

That is, the image display device 1 of the second embodiment providesonly the image L2 to the viewer 10 and only the image R2 to the viewer20 in the first dual-screen display mode. In the second dual-screendisplay mode, the image display device 1 provides only the image R2 tothe viewer 10 and only the image L2 to the viewer 20.

The image display device 1 of the second embodiment described above hasthe following advantages.

In the image display device 1 of the second embodiment, images providedto the viewers 10 and 20 at different viewing positions can be switchedby changing the manner in which the polarization-controlled liquidcrystal panel 7 is controlled, without changing the image data inputfrom the external device to the controller 30 or the image signalssupplied from the controller 30 to the display panel 2. That is, thedirections in which images are displayed can be switched.

For example, when similarly switching the directions in which images areprovided, a known dual-screen display device using a parallax barrierinvolves switching the positions at which the images L2 and R2 aredisplayed. Therefore, in the known dual-screen display device, the inputimage data needs to be re-rendered and new image signals need to begenerated every time the positions at which images are displayed areswitched. When switching the directions in which images are displayed,it requires time for the known dual-screen display device to re-renderthe image data, resulting in a delay in displaying images. To preventthe delay in displaying images, an additional memory is necessary, whichleads to an increase in the cost of the display device.

However, in the image display device 1 of the second embodiment, theimages provided to the viewers 10 and 20 at different viewing positionscan be switched instantly without needing to switch the positions atwhich the images L2 and R2 are displayed. As a result, no delay occursin displaying the images upon the switching operation. Therefore, theviewers 10 and 20 can view the images L2 and R2 in a more comfortablemanner. There is no need to have an additional memory, and the imagedisplay device 1 can be fabricated at low cost.

In the second embodiment, the first and second dual-screen display modesof the image display device 1 are switched by giving an image displaymode switching command from the external device to the controller 30.However, the display mode switching is not limited thereto. For example,the first and second dual-screen display modes may be sequentiallyswitched every predetermined time using a timer.

The other advantages of the second embodiment and the structure of anelectronic apparatus are the same as those of the first embodiment.

The invention is not limited to the embodiments described above. Variouschanges, alterations, and modifications are possible without departingfrom the scope of the invention set forth in claims and the entirespecification.

1. An image display device comprising: a display panel that has aplurality of pixels arranged in a predetermined first direction and in asecond direction intersecting with the first direction; a light sourcethat emits light to the display panel; a controller; a polarization axiscontroller that separates the light emitted from the light source intolight with a first polarization axis and light with a secondpolarization axis different from the first polarization axis, thepolarization axis controller being disposed between the display paneland the light source; and an optical element that directs the lightemitted from the light source in a direction substantially orthogonal tothe first direction, the optical element being disposed between thedisplay panel and the polarization axis controller, wherein thepolarization axis controller includes a first substrate, a secondsubstrate, a liquid crystal layer held between the first substrate andthe second substrate, a plurality of first electrodes disposed on thefirst substrate so as to extend in the first direction, the plurality offirst electrodes being arranged at a predetermined interval in thesecond direction, and a plurality of second electrodes disposed on thesecond substrate so as to extend in the first direction, the pluralityof second electrodes being arranged at an interval twice thepredetermined interval in the second direction, wherein the plurality ofsecond electrodes is disposed so as to overlap at least part of theadjacent first electrodes, wherein the controller switches an imagedisplay mode between a dual-screen display mode and a three-dimensionalimage display mode by controlling voltages applied to the plurality offirst electrodes and the plurality of second electrodes, wherein in thedual-screen display mode, the controller applies voltages to theplurality of second electrodes so that the adjacent electrodes haveopposite phases, and, to the plurality of first electrodes, applies avoltage having the same phase as one of the voltages applied to theplurality of second electrodes, and wherein in the three-dimensionalimage display mode, the controller applies voltages to the plurality offirst electrodes so that the adjacent electrodes have or oppositephases, and, to the plurality of second electrodes, applies a voltagehaving the same phase as one of the voltages applied to the plurality offirst electrodes.
 2. The image display device according to claim 1,wherein the plurality of first electrodes is a plurality of stripelectrodes of a pair of comb-like electrodes having a pair of connectingportions disposed along an outer periphery of the first substrate andthe plurality of strip electrodes extending alternately from the pair ofconnecting portions inward of the first substrate, and wherein theplurality of second electrodes is a plurality of strip electrodes of apair of comb-like electrodes having a pair of connecting portionsdisposed along an outer periphery of the second substrate and theplurality of strip electrodes extending alternately from the pair ofconnecting portions inward of the second substrate.
 3. The image displaydevice according to claim 1, wherein the controller applies the voltagesto the plurality of first electrodes so that the adjacent electrodeshave opposite phases and, to the second electrodes, applies a voltagewith a period half that of the voltages applied to the plurality offirst electrodes, thereby switching the image display mode to atwo-dimensional image display mode.
 4. The image display deviceaccording to claim 1, wherein the controller applies the voltages to theplurality of second electrodes so that the adjacent electrodes haveopposite phases, and, to the plurality of first electrodes, applies avoltage having the same phase as the other voltage applied to theplurality of second electrodes, thereby switching the image display modeto a second dual-screen display mode.
 5. An electronic apparatuscomprising an image display device as set forth in claim 1.